Black mold or algae on driveway! HELP!!

I moved to Florida from New York State in May 2018. There was a lot of green, yellow and black algae on my driveway. After pressure washing it, the green and yellow algae was gone, but I had residual black algae left, although it was improved. They are quarter sized circles. I then tried outdoor bleach, first mixing it as directed, then using it full strength, then mixing it full strength with TSP, each time leaving it on for 30 minutes and scrubbing. Nothing worked. The first week of June 2018 I applied Wet and Forget, and so far I have not noticed any change in the black areas. Does any one have any other suggestions as to what I can try next? Thank you!